Dynamo-electric machines



Nov. 3, 1959 E. BARLOW DYNAMO-ELECTRIC MACHINES Filed Oct. 10, 1956 United States Patent V 2,911,552 DYNAMO-ELECTRIC MACHINES Application October '10, 1956 Serial No. 615,044

Claims priority, application Great Britain October 13, 1955 2 Claims. (Cl. 310-258) This invention relates to dynamo-electric machines and is particularly concerned with the construction of stators for large dynamo-electric machines.

With the ever-increasing size of dynamo-electric machines, particularly of generators, difficulty is experienced in transporting the stators to their final erection sites. Although a certain amount of assembly work can be carried out on site, it is obviously desirable that the stator should be assembled in the factory prior to transportation.

It is an object of the present invention to provide a stator construction which can be built up into a small number of parts that can be conveniently assembled at the final site to form the complete stator.

According to the present invention a stator for a dynamo-electric machine comprises an outer frame in the form of a substantially cylindrical annulus provided with one or more substantially plane surfaces extending axially thereof along the interior of the annulus and an inner frame positioned within said annulus and having corresponding plane surfaces co-operating with the plane surfaces on the outer frame, whereby the inner frame is borne within the outer frame.

Preferably, the outer frame is provided with two plane surfaces, each arranged on respective opposite sides of the axis of the stator. The surfaces may be provided by bars extending the length of the stator on which the corresponding surfaces of the inner frame can rest and be bolted thereto. These corresponding surfaces on the inner frame may be provided by feet extending substantially the length of the frame.

In a preferred embodiment of the invention, the inner frame consists of core laminations for carrying the stator windings and supported by core bars which are spaced circumferentially round the outer periphery of the core and interconnected by webs so as to form a unitary structure and the outer frame consists of an outer shell with interconnecting webs and suitable radial and tangential ribs.

In a preferred construction of the outer frame, it is formed of two substantially semi-cylindrical sections, which in the final assembly of the stator are sealed together in a gas tight manner.

The supports for the inner frame need not necessarily be on the same level as the joints between the top and bottom halves of the outer frame, but can be either higher or lower as the design of the stator permits.

The core bars may be flexibly connected to the Web plates of the inner frame in the manner disclosed in co-pending application No. 583,426, new Letters Patent No. 2,811,659 issued October 29, 1957.

In order that the invention may be more fully understood reference Will now be made to the accompanying drawing, the single figure of which shows a section through a stator embodying the invention.

Referring to the drawing, the inner frame consists of a laminated steel core 1 which carries the stator windings. The core is supported on core bars 2 which can be rigidly connected or flexibly connected, as for instance 2,911,552 C Patented'Nov. 3, 1959 disclosed in co-pending application No. 583,426 into web plates 3. The webs are spaced axially and are held in position by the axial bars 4. Additional stiffness is provided by the radial plates 5. Rectangular cross section bars 6 are welded to the Webs which are suitably shaped to receive them, these bars forming the feet on Which the inner frame stands. Cool gas can be conveyed axially from the outlet side of the ventilation fans to parts of the core near the generator centre line by means of the pipes 7 Welded into the webs. The pipes discharge into a chamber between two webs and the gas is prevented from escaping radially outwards by welding a thin cover plate 8 on to the webs.

The outer frame is made from webs 9 axially spaced and welded to the inside of the cylindrical enclosing plate 10, radial plates 11 providing stiffening. The frame is one piece or preferably divided into two (or more) parts, and the parts are fastened together by a gas tight joint. The joint is formed by welding to the outer casing and webs, two bars 12 of suitable rectangular cross-section to provide rigid faces which are bolted together. Grooves in the sealing faces will carry a suitable sealing material. The outer frame will be arranged to carry gas coolers 13 and to provide passages for the gas entering the coolers 14 and for the gas moving from the coolers to the fans 15. Bars 16 will be welded across the Webs to provide a support onto which the feet of the inner frame will rest.

To assemble the stator, the lower half of the outer frame can be mounted on the generator foundations, and then the inner frame can be dropped into position inside the half outer frame and then bolted down to the support bar 16. The upper half outer frame can then be dropped into position over the inner frame and the gas tight joints bolted up and the seal made.

Alternatively, the outer frame can be completely assembled and mounted on the foundations. The inner frame will then be threaded axially into the outer frame bore.

It can thus be seen that the inner frame is a completely separate unit. The only connection between the inner and outer parts is at the feet. There is no need for any internal sealing plates between the two parts, although external sealing plates will be required at each end. The webs in the inner and outer parts do not need to coincide with each other, this gives freedom to arrange them to suit the particular requirements of each part.

The stator described herein thus comprises two or more structures each of which can be transported separately. The structures are themselves within transport limits With regard to size and weight and are complete in themselves. The only work required when assembling on site is the making of gas tight bolted joints.

What I claim is:

1. A stator for a dynamo-electric machine comprising an outer frame in the form of a substantially cylindrical annulus, said outer frame consisting of an outer shell with inter-connected webs and suitable radial and tangential ribs, two substantially plane strip-like surfaces extending axially of the length of the stator on respective opposite sides of the interior of said outer frame, and an inner frame adapted to be positioned within said outer frame on assembly of the stator, said inner frame consisting of core laminations for carrying the stator windings and supported by core bars which are spaced circumferentially round the outer periphery of the core and interconnected by webs so as to form a unitary structure, and corresponding plane strip-like surfaces provided on said inner frame arranged to rest on said plane surfaces on said outer frame whereby said inner frame is borne within said outer frame.

2. A stator for a dynamoelectric machine comprising an annular outer frame in the form of a lower semicylindrical section and an upper semi-cylindrical section, said two sections being arranged to be bolted together on assembly of the stator, and each of said sections consisting of an outer shell with interconnected webs and suitable radial and tangential ribs, two substantially plane strip-like surfaces extending axially of the length of the stator on respective opposite sides of the interior of said lower section, and an inner frame consisting of core laminations for carrying the stator windings and supported by core bars which are placed circumferentially round the outer periphery of the core and interconnected by Webs so, as to form a unitary structure and corresponding plane strip-like surfaces provided on said inner frame arranged to rest on said plane surfaces on the lower 4' i section of said outer frame whereby said inner frame is borne within said outer frame on assembly of the stator.

References Cited in the file of this patent UNITED STATES PATENTS 1,689,503 Savage Oct-30, 1928 1,749,728 Wood Mar. 4, 1930 2,320,843 Baudry June 1, 1943 FOREIGN PATENTS r 453,910 France Apr. 16, 1913 619,353 Germany Sept. 28, 1935 873,285 Germany Apr. 13, 1953 

